Method of producing granules of magnesium and its alloys

ABSTRACT

The method is based on the introduction to liquid metal at the temperature of 670*-720*C of a salt heated to the temperature of 670*-730*C, composed of metal chlorides and fluorides not reducible by magnesium taken separately or in combination, and having an initial crystallization temperature below that of the granulated metal, and a density at the temperature of 670*-730*C equal to 0.95-1.2 of the density of the metal.

United States Patent [191 Barannik et a1.

[451 May 6,1975

[ METHOD OF PRODUCING GRANULES OF MAGNESIUM AND ITS ALLOYS [76]inventors: Ivan Andreevieh Barannik, ulitsa Lenina, 182a, kv. 22,Zaporozhie; lvanovich Belkin, uiitsa Kaliinaya, 7, kv. 13 Solikamsk;Viktor lvanovich Borodin, ulitsa Fersmana, 18, kv. l3, ApatityMurmanskoi oblasti; Natalya Alexandrovna Voronova, pereulok Uritskogo,11, kv. 4, Dnepropetrovsk; Oleg Nikolaevich Romanenko, ulitsaSevastopolskaya, 6, kv. 46, Kalush lvano-Frankovskoi oblasti; AlexandrPetrovich Bogdanov, bulvar Tsentralhy, 3, kv. 44, Zaporozhie; ValerySergeevich Belosludtsev, ulitsa Kaliinaya, 114, kv, 13; VladimirDmitrievich Marlin, ulitsa Kaliinaya, 153, kv. 153, both of Solikamsk;Nikolai Yakovlevich Shish, ulitsa Gryaznova, 88 kv. 3, Zaporozhie;Anatoly Filippovich Shevchenko, ulitsa G. Pushkina, 1b, kv. 52; IvanYakovlevich Emelyanov, ulitsa, G. Pushkina, 1b, kv. 58, both ofDnepropetrovsk; Jury Nikolaevich Boiko, prospekt Lenina, 155, kv. l0,Zaporozhie; Mikhail Nikolaevich Kljuchnik, ulitsa Kalinovaya, 94, kv.46, Dnepropetrovsk; Nikolai Vasilievieh Khaber, ulitsa Sevastopolskaya,4, kv. 6, Kalush lvano-Frankovskoi oblasti; Viktor Georgievich Raskatov,ulitsa Khimikov, 14, kv. l8, Kalush lvano-Frankovskoi oblasti; AlexandrFedorovich Trukhin, ulitsa Zhdanova, 11, kv. 32, Kalushlvano-Frankovskoi oblasti; Anatoly Borisovich Kondratenko, ulitsaSevastopolskaya, 4, kv. 36, Kalush lvano-Frankovskoi oblasti; VladimirDmitrievich Yamev, ulitsa Bogdana Khmelnitskogo, 66, kv. 59, Kalushlvano-Frankovskoi oblasti; Viktor Stephanovich Alontsev, ultisaKaliinaya, I24, kv. l5; Valery Alexeevich Startsev, ulitsa Kaliinaya,124, kv. 4, both of Solikamsk; Jury Alexandrovich Sergeev, prospektLenina, 182a, kv. 23, Zaporozhie, all of USSR.

22 Filed: Feb. 19, 1974 211 Appl. No.: 443,845

Primary Examiner-L. Dewayne Rutledge Assistant Examiner-Arthur .l.Steiner [57] ABSTRACT The method is based on the introduction to liquidmetal at the temperature of 670720C of a salt heated to the temperatureof 670730C, composed of metal chlorides and fluorides not reducible bymagnesium taken separately or in combination, and having an initialcrystallization temperature below that of the granulated metal, and adensity at the temperature of 670730C equal to 0.95-l.2 of the densityof the metal.

11 Claims, No Drawings 1 METHOD OF PRODUCING GRANULES F MAGNESIUM ANDITS ALLOYS The molten mixture is atomized by centrifugal force withsubsequent cooling of the thus produced discrete particles by air flow.

The mixture obtained in producing granules of magnesium or its alloyscomprises in weight per cent: 6597 of granulated magnesium, 0.3-16 ofmagnesium and alkali metal chlorides, 0.1- of one of the fluorides, upto 3 of alkaline-earth metal chlorides, up to 6 of magnesium oxide.

The above mixture can also comprise in weight per cent: 60-97 ofgranulated magnesium alloy, 0.3-l6 of magnesium and alkali metalchlorides, 0.1-10 of one of the fluorides, 03-10 of alkaline-earth metalchlorides, and not over 5.0 of magnesium oxide.

The invention relates to methods of producing discrete solid metalparticles and in particular granules of magnesium and magnesium-basealloys.

A method is known of producing granules of aluminium and magnesium ortheir alloys by centrifuging liquid metal with the help of a rotatingdisk, bowl or perforated cup. In this method of producing particles ofmagnesium or magnesium-base alloys the centrifuging and subsequentcooling of produced particles are effected in a medium of gases whichare inert with respect to magnesium (U.S. Pat. No. 2,699,576, 2,676,359,2,934,789).

Also known is a method of producing granules of magnesium and its alloysby atomizing liquid metal, consisting in that a salt is introduced intothe liquid metal prior to atomization having a melting temperature abovethat of magnesium, for example alkali and alkali-earth metalchlorides inthe amount of 2-20 per cent by weight. However, the above methods ofproducing granules of magnesium have the following disadvantages:

application of the protective atmosphere of inert gases makes theprocess costly and relatively complicated in terms of equipment needed,while using such gases as hydrogen, methane, propane and the like alsoadds an explosion hazard to the process;

introduction into the molten metal of a salt having a meltingtemperature higher than that of magnesium affords no reliable protectionof the dispersed liquid metal against oxidizing by atmospheric oxygen,which makes the process actually uncontrolled because of the periodicignition of the magnesium in the course of the dispersing. This leads tothe production of randomly shaped particles with heavily oxidizedsurfaces.

The object of the present invention is to provide a method of producinggranules of magnesium or its alloys by centrifuging molten metal with asalt addition which possesses a certain combination of physical andchemical properties permitting the process to be carried out in air toproduce granules of given shape and required quality (in terms of itschemical composition).

Another object of the invention is to select a salt addition of suchchemical composition and amount which besides making possible the normalgranulating process in air also makes it possible to producemagnesiumcontaining mixtures comprising the required amount of metalgranules and added salt in the form of granules and of a thin film onthe surface of the metal granules, to make the mixture less hygroscopicand less flammable.

One more object of the invention is to produce such mixtures which makeit possible to increase the rate of ultilization of magnesium used intreating cast iron and other metals for desulphurization or inoculation.

Still another object of the present invention is to provide a process ofgranulation with salt additions which besides assuring the normaloperation of the granulating process can be easily removed by furtherhydrochemical treatment to produce granulated magnesium or its alloy notinferior in terms of activity to magnesium powders produced by millingor atomization in an inert atmosphere.

These and other objects are achieved by a method of producing granulesof magnesium or its alloys, consisting in the simultaneous delivery intothe centrifugal granulator of continuous flows of liquid magnesium orits alloy and a salt which is a mixture of magnesium chloride and atleast one salt selected from the group of alkaline and alkali-earthmetalchlorides, breaking the mixture of liquid magnesium or its alloyand the added salt by the action of centrifugal force into discreteliquid particles with subsequent cooling of the produced granules inair. According to the invention the added salt mixture comprises suchcomponents and in such quantities that the initial crystallizationtemperature of the salt addition is below that of magnesium, and itsdensity at 670-730C is equal to O.95l.2 of the density of liquidmagnesium or its alloy in the same temperature range. The delivery intothe centrifugal granulator of magnesium or its alloy is effected at atemperature within the range of 670-720C, and the salt addition at atemperature within the range of 670730C.

The salt addition prepared according to the above requirements, whenmaintaining the above-mentioned temperature range in heating the saltaddition and liquid metal, provides reliable protection for droplets ofliquid magnesium or magnesium alloy produced during the centrifugalatomization, against direct contact with atmospheric oxygen before theirsolidification into granules.

The salt addition having a lower melting temperature than magnesium anda density close to that of magnesium is centrifuged simultaneously withthe metal and spreads in the form of a thin salt film over the surfaceof each metal droplet, thus protecting it against contact withatmospheric oxygen. This protective action of the salt film may continueup to the moment of its crystallization which should come after thesolidification of the metal particle. If crystallization of the saltaddition takes place before the solidification of the metal protectedthereby, intensive oxidation of the metal granule occurs, oftenaccompanied by ignition.

Instability of the granulating process shown by intensive oxidation(burning) of magnesium in the course of its atomization and resulting ingranules with heavily oxidized surfaces and random shapes may be causedby overheating the metal in excess of 720C or, on the other hand, itsinsufficient heating to less than 670C.

The temperature of the salt addition at the moment of bringing it to theliquid metal should be approximately equal to the temperature of metal,however consideration should be taken of its initial crystallizationtemperature. Substantial heating of the salt addition in excess of itsmelting temperature leads to the undesirable effect of producing a solidconglomeration consisting of metal granules cemented to each other bythe salt addition which because of the high degree of heating thereofhas no time to solidify until the moment of striking the wall of thegranule-collecting chamber. Carrying out the granulating process withinsufficient heating of the salt addition causes its prematuresolidification on the surface of the not yet solidified metal particlesand consequently the intensive oxidation of these particles by airoxygen.

To reduce hygroscopicity and increase corrosion resistance of themetal-salt mixture formed after cooling down to the granules ofmagnesium or its alloy and added salt, the salt addition according tothe invention includes 05-10 per cent by weight of magnesium, sodium andalkaline earth metal fluorides taken separately or in combination. It isknown that magnesium, sodium and alkaline-earth metalfluorides are lesshygroscopic salts than the similar chlorides. Besides, fluorides areknown to improve corrosion resistance of magnesium and its alloys byforming on the metal surface of a thin protective fluoride film.However, application of a salt addition composed merely of fluorides isdifficult because of the high melting temperature of fluorides.Furthermore it hampers the subsequent hydrochemical treatment ofgranules because in practice they are not soluble in water. Therefore,to produce granulated magnesium-containing mixtures it is preferred inpractice to have a salt composition with the minimum amount of fluorideswhich are fully transferred into the produced granulated metal-saltmixture, thus improving its corrosion resistance. Moreover, utilizationof fluorides in certain processes of treating liquid metal, for examplecast iron and ferroalloys, is desirable as it may be instrumental inupgrading metal by removing harmful impurities.

The actual composition of the salt additions meeting the above describedrequirements may be widely varied. However, there are a number ofoptimum compositions whose formulation requires the followingconsiderations to be taken in mind:

melting temperature of the salt addition should be higher than that ofmagnesium;

density of the salt addition should be equal to 0.95-1.2 of the densityof the liquid metal in the temperature range of 670730C:

the molten salt melt should efficiently wet the liquid metal withoutbeing reduced by the latter;

the salt metal after solidification should be of minimum hygroscopicity;

the salt mixture, other things being equal should least affect thecorrosion resistance of granulated magnesium;

the salt mixture should be inexpensive and contain the minimum amount ofhigh-melting admixtures such as magnesium oxide.

These requirements are met by the following compositions of the saltaddition.

According to the invention, liquid magnesium may use the salt additioncomprising in per cent by weight:

40-65 KC], 25-50 NaCl, 3-10 MgCl up to 5CaCl up to 0.8 F,

not over 0.5 MgO.

Liquid magnesium alloy according to the invention may use the saltaddition comprising in per cent by weight:

10-40 MgCl up to 5.0 CaCl up to 0.8 F

not over 0.8 MgO,

3-15 BaCl the balance NaCl.

Magnesium oxide is an undesirable admixture impairing the granulatingprocess, therefore conditions should of necessity be provided during thepreparation of salt additions to prevent the formation of magnesiumoxide in the melt.

For the purpose of producing a magnesiumcontaining granulated materialpossessing minimum hygroscopicity and high corrosion resistance, liquidmetal according to the invention may receive a salt addition composed ofthe less hygroscopic sodium and potassium chlorides taken in proportionof L1 to 1.5 and sodium fluoride taken in the amount of 0.5-]0 per centby weight, and the total content of the more hygroscopic barium,magnesium and calcium chlorides should not be over 5 per cent by weight.

The selected combination of sodium and potassium chlorides approximatelycorresponds to an equimolecular mixture with the minimum meltingtemperature (-650C); addition of fluorides brings a further lowering ofthe melting temperature and a certain increase of the density of thesalt addition and, what is of principal importance, improves corrosionresistance of the material produced.

For granulating pure magnesium, the content of alkaline-earth metal (Ba,Ca, Mg) chlorides should be reduced to the minimum, with the permissibleoccurrence of magnesium chloride in the amount of 2-3 per cent byweight. In granulating a magnesium alloy, preference should be given tobarium chloride for the purpose of increasing the density of the saltaddition.

Application of the above described compositions of salt additions takingaccount of the necessary relation of melting points of said saltadditions and liquid metal provides conditions for the realization ofthe controlled granulating process.

To produce granulated metal comprising not less than 50 per cent ofgranules of spherical and ellipsoidal shapes according to the inventionthe liquid metal should receive the salt addition in the amount of 2.5to 20 per cent by weight. With this, the larger the use of the saltaddition within the indicated limits, the more granules will havespherical or ellipsoidal shape. With salt addition used in the amount of20 percent by weight the product will practically include per cent ofspherical and ellipsoidal particles.

To produce granulated metal comprising not less than 50 per cent ofelongated granules whose length is at least twice their diameter, theliquid metal should re ceive 0.5-2.5 per cent by weight of the saltaddition. With the reduction of the amount of the salt addition below2.5 per cent by weight the content of elongated particles in granulatedmagnesium increases.

Granules of magnesium-containing mixtures produced during the process ofatomization in air, after being cooled down and sieved, represent acommercial product to be used in desulphurization, deoxidation andinoculation of cast iron, steel, ferroalloys.

In addition to that, the disclosed method opens the way for theproduction of granulated magnesium and its alloys which in terms ofpurity and the content of active magnesium are not inferior to magnesiumpowders produced by more expensive methods (milling or atomization inthe atmosphere of hydrocarbon gas or inert gas).

To produce such material according to the invention, granulated metalafter being air cooled down to 600-100C is subjected to thehydrochemical treatment within 0.55-5 min. The combination of thedisclosed method and the hydrochemical treatment makes the lattertreatment cheaper due to the utilization of the heat of granules.Besides, the hydrochemical treatment process itself becomessubstantially simpler in comparison with known processes for treatingproducts made of magnesium alloys.

For the hydrochemical treatment according to the invention, use can bemade for example of 1-10 per cent solution of alkali metal bichromate ata temperature of l035C and with the weight ratio of the mixture ofgranules to the solution from 1:2 to 1:20. After being subjected to thehydrochemical treatment and drying by known and appropriate methods, thegranulated magnesium may comprise 9899.6 per cent by weight of activemagnesium.

The method of the present invention, in our judgement, is universalbecause it permits the production of a wide range ofmagnesium-containing granulated materials able to meet the requirementsof diverse consumers metallurgical, foundry and chemical industries.Thus, mixtures obtained during the production of granules of magnesiumand its alloys are successfully used in desulphurization and inoculationof cast iron with a higher efficiency in comparison with the use ofmagnesium powders produced by the milling method. The mixtures producedaccording to the invention are looser in nature, have the bulk weight of0.9 to 1.2 g/cm, carry no explosion hazard, while the temperature oftheir self-ignition is 400500C higher than of magnesium powders producedby the milling method.

The mixture obtained during the production of granules of magnesium andits alloys according to the ivention may comprise in per cent by weight:

65-97 granulated magnesium,

0.3-16 magnesium and alkali metal-chlorides,

0.1- one of said fluorides,

up to 3.0 alkali-earth metal-chlorides,

not over 6.0 magnesium oxide.

The mixture obtained during the production of granules of magnesium andits alloys according to the invention may also comprise in per cent byweight:

60-97 granulated magnesium alloy,

0.3-16 magnesium and alkali metal chlorides,

0. l10 one of said fluorides,

0.3-10 alkali earth-metal fluorides,

not over 5.0 magnesium oxide.

The most corrosion-resistant mixtures according to the invention arethose mixtures in which the salt addition composed of chlorides andfluorides comprises in per cent by weight: not over 5.0 of magnesium,calcium and barium chlorides taken separately or in combination, up to2.0 of sodium and magnesium fluorides, the balance sodium and potassiumchlorides taken in a proportion of 1.1 to 1.5.

The corrosion resistance of the mixture is improved by a reduction inthe general hygroscopicity of component salts included therein, as wellas by the passivation of granules by means of fluorine ions introducedinto the salt addition in the form of sodium or magnesium fluoride.

Depending on the process conditions described above, granulatedmagnesium can be obtained containing more than 50 per cent of sphericalor ellipsoidal granules. This material is of good fluidity and itsutilization is preferable in processes where air conveyance facilitiesare used. It is also possible to obtain granulated magnesium containingmore than 50 per cent of elongated granules whose length is at least twotimes their thickness. This material is of less fluidity but featuresbetter mouldability and larger overall surface area. Such material ispreferable for use in the production of various compositions with othermaterials. For example, it may be used in producing ferro-magnesium orferro-silicon-magnesium briquettes for inoculating cast iron.

By subjecting granulated magnesium to a hydrochemical treatment, say, inalkali metal bichromate, granulated magnesium can be purified fromchloride and magnesium oxide admixtures, yielding a product consistingchiefly of spherical or ellipsoidal granules or elongated granules withthe minimum content of chlorides (chlorine ions) and oxide.

Thus, a material is produced wherein the content of chlorine ions is notover 0.4 per cent by weight and that of magnesium oxide is up to 1.0 percent by weight.

A number of actual examples of the above method and the materialsproduced by using same will now be described.

EXAMPLE 1 A chamber-enclosed centrifugal granulator is employed topulverize liquid electrolytic magnesium having the temperature of 720Cwith the rotational speed of the perforated cup equal to 1,000 rpm. 1nthe course of pouring into the granulator, magnesium receives 05 percent by weight of the salt addition heated to the temperature of 730C.The salt addition is of the following composition in per cent by weight:10.0 MgCl,, 48.0 KC], 39.08 NaCl, 2.0 CaCI 0.02 MgO.

Liquid particles of the magnesium-salt mixture flung through the holesin the rotating cup by the action of the centrifugal force are cooled intheir flying trajectory by the counter air flow drawn through thechamber by means of the fan.

After becoming solidified, the granules produced thereby consisted inper cent of elongated fused particles in the form of commas or stringswhose diameter in the thickest portion was 0.4 to 2 mm and the length lto 15 mm.

The above product has been analyzed for the content of chlorion (Cl) (anindicator of the residual content of chlorides in granules of magnesium)and magnesium oxide.

The results of the analysis revealed that this product included per centby weight: 0.21 chlorion (CI"), 2.8 MgO and 0.lF

EXAMPLE 2 The process conditions are similar to those described inExample 1, but the amount of the salt addition is increased to 2.1 percent by weight.

Granulated magnesium produced thereby consisted in 60 per cent ofelongated granules shaped as described in Example 1, while the remaining40 per cent were spherical or ellipsoidal granules 0.4 to 2.5 mm indiameter coated with a thin salt film.

Granulated magnesium produced thereby had a content of 1.1 per cent byweight 1.1 chlorion and 3.2 MgO.

EXAMPLE 3 The process conditions are similar to those described inExample 1, but the amount of the salt addition is increased to 2.6 percent by weight.

Granulated magnesium produced thereby consisted in 55 per cent ofspherical or ellipsoidal granules, while the remaining 45 per cent wereelongated granules shaped as described in Example 1.

Granulated magnesium produced thereby had a content in per cent byweight of: 1.5 chlorion and 2.5 MgO.

EXAMPLE 4 The process conditions are similar to those described inExample 1, but the amount of the salt addition is increased to 20 percent by weight.

Granulated magnesium produced thereby included 1.5 per cent of elongatedgranules, while the remaining granules were of regular spherical orellipsoidal shape. Granules are coated with a thin salt film.

Apart from metal granules the product contained about 6 per cent ofspherical salt addition particles.

The results of the chemical composition analysis of the product obtainedin per cent by weight: 9.5 chlorion, traces of MgO.

EXAMPLE 5 The process conditions are similar to those described inExample 4, but the salt addition contains 0.2 per cent by weight F.

Granulated magnesium produced thereby included 95 per cent ofball-shaped granules, 0.4 to 2.5 mm in diameter.

The results of the chemical composition analysis in per cent by weight:8.3 chlorion, 0.03 F, MgO not found.

EXAMPLE 6 A chamber-enclosed granulator is employed to pulverize liquidmagnesium alloy containing 8 per cent by weight Al and 1.0 per cent byweight Zn with the rotational speed of the perforated cup equal to 1,200rpm.

The cup diameter is 100 mm, the diameter of working holes 1.2 mm.

Before pouring into the granulator, liquid magnesium alloy was heated tothe temperature of 680C.

The alloy was given 0.5 per cent by weight of the salt addition of thefollowing composition in per cent by weight: 40 MgCl 43 KC], 6 NaCl, 10BaCl 0.6 CaCl 0.2 F and 0.4 MgO.

Temperature of the salt addition before introduction to the alloy was700C;

Liquid particles of magnesium alloy and salt addition flung from theworking holes of the rotating cup were cooled by counter flows of airdrawn through the chamber by means of a fan.

Granules produced thereby after becoming solidified consisted of 80 percent of elongated fused particles in the form of commas or strings.

The results of the analysis revealed that this product included in percent by weight: 0.24 chlorion, 3.0 MgO and 1.0 F.

EXAMPLE 7 The process of granulating magnesium alloy including per centby weight: 8.0 A] and 1.0 Zn is carried out similarly to that describedin Example 6, but with the amount of the salt addition of the samecomposition equal to 12 per cent by weight of the alloy beingpulverized.

The product consisted of per cent of spherical and ellipsoidal granuleswhich, when sieved on standard sieves, passed through 2.5 mm holes. Theresults of the chemical analysis revealed that this product included percent by weight: 5.2 chlorion and 0.1 F.

EXAMPLE 8 Raw magnesium is heated to 700C and given 10 per cent byweight of the salt addition heated to 720C of the following chemicalcomposition per cent by weight: 2 MgCl 53.5 KC], 44 NaCl, 0.5 NaF. Themixture of magnesium and salt addition is atomized by means of therotating perforated cup mm in diameter, with the diameter of workingholes equal to 1.5 mm. The cup rotates at the speed of 1,000 rpm.

After being cooled down in air, the product was subjected to sieve andchemical analyses.

The product contained 85 per cent of spherical granules sized 0.52.5 mm.The results of the chemical analysis in per cent by weight: 4.0 Cl, 0.1MgO, 0.15 of F.

EXAMPLE 9 Granules produced by the method described in Example 8 are aircooled down to a temperature of 100C and then submerged for 0.5 min in avessel containing a 1 per cent solution of K Cr O-, with the initialtemperature of 35C.

The ratio between the amount of granules and that of the solution is1:2. After a 0.5 min period the granules are removed from the solutionand dried at a temperature of C for 1 hour.

The above product was analyzed for the content of chlorion and magnesiumoxide.

The results of the analysis: 0.36 per cent by weight Cl, 0.6 per cent byweight MgO.

EXAMPLE l0 Granules produced by the method described in Example 8 arecooled down to 600C and submerged in a vessel containing a 5 per centsolution of K- .Cr O having a temperature of 10C, the ratio of theamount of granules to the mass of the solution being 1:20.

After a 2 min period the granules are removed from the solution, washedin water and dried during 1 hour at a temperature of 120C in a dryingcabinet.

The results of the chemical analysis of the above granulated magnesiumin per cent by weight is as follows: 0.02 CI, 0.1 MgO.

EXAMPLE 1 1 Several versions of granulated magnesium and its alloysproduced by the methods described in Examples l-8 were subjected to acomparative test of properties.

Actual compositions of the samples are given in Table l.

Table 1 Composition Content in weight percent Sample I Sample 2 Sample 3Sample 4 Sample 5 Granulated magnesium 96.0 80.0 89.1 92.5 Granulated96.0 magnesium Chlorine ions 0.2l 9.5 0.24 5.2 4.0 Fluorine ions 0.] 0.]0.1 0.15 Magnesium oxide 28 3.0 0.1

Shape of particelongated spherical. elongated spheri- Spherilesellipsoidal cal. cal 85 ellipper cent soidal elongated per cent Ignition650 1000 620 920 900 temperature.

Bulk weight, 0.83 1.0 0.91 1.2 0.98 g/cm" Table 2 Results of desul'phurization Sample No. 2 Sample No. 4 Sample No. 5

Final sulphur 0.03 0.03 0.026 content in cast iron in percent by weightCharacter of desulvigorous vigorous process inphurization process"boiling boiling of tensity twice of cast iron cast iron calmer thanwith liberawith liberawith Samples tion of large tion of large Nos. 2and 4 amount of amount of smoke smoke Note! The invented method ofproducting granules of mag- SamplB 1 pr ced y thc method deSCrlbed mnesium and its alloys opens a way to obtain granules of Example 40 thegiven shape and the required chemical composi- Sample No. 2 produced bythe method described in fl Example 2. Moreover, the given method permitsselecting a salt Sample No. 3 produced by the method described inaddition of a chemical composition which assures the Example 3- normaloperation of the granulating process in air to Sample N0- 4 Pr du y them t d dflSCribed in produce magnesium-containing mixtures consisting ofExample 4. the desired amounts of metal granules and added salt. SampleNo. 5 produced by the method described in The salt is found in themixture both in the form of Example 5. granules and in the form of athin film covering the sur- The samples were tested for corrosionresistance in humid atmosphere for which purpose they were kept abovewater in an dessicator for 12 hours.

After the 12-hour period of keeping above water the samples were driedand their moisture content was determined by the change of their weightbefore and after the treatment in the dessicator.

Sample Nos. 2 and 4 revealed a weight increase of 12-15 per cent,samples No. l and 3 3 per cent, sample No. 5 3.5 per cent.

Samples Nos. 2, 4, 5 were tested in desulphurization of cast iron. Theprocess of desulphurization was carried out in a 60-t capacity ladle byinjecting magnesium or magnesium alloy granules into cast iron bycompressed air with the help of a tuyere.

The amount of the product used in all tests was equal to 0.35 kg per 1 tof cast iron. The initial sulphur content in cast iron 0.045 per cent byweight.

The results of desulphurization are given in Table 2.

face of metal granules, thus making the mixture explosion-proof and lessflammable.

The present invention allows such mixtures to be produced which areinstrumental in increasing the rate of utilization of magnesium whenused for treating cast iron and other metals for the purpose ofdesulphurization or inoculation.

The granulating process performed with the above salt additions assuresthe normal operation of the granulating process and easy removal of thesalt by subsequent hydrochemical treatment. This makes it possible toproduce granulated magnesium or its alloys which in activity arepractically equivalent to magnesium powders produced by milling oratomizing in inert atmosphere.

What we claim is:

l. A method of producing granules of magnesium or its alloys including:heating liquid magnesium or its alloy to a temperature within the rangeof 670720C;

preparing a salt addition which is a mixture of magnesium chloride andat least one component selected from the group consisting of alkali andalkaline-earth metal chlorides taken in such combination and in suchquantitative composition that the initial crystallization temperature ofthe salt addition is below that of magnesium, and its density at 670730Cis equal to 0.95-1.20 of the density of liquid magnesium or its alloy;heating said salt addition to a temperature within the range of670-730C; simultaneously delivering said liquid magnesium or its alloyand the salt addition in continuous streams into a centrifugalgranulator; breaking the mixture of liquid magnesium or its alloy andthe salt addition into discrete liquid particles by the action of thecentrifugal force; cooling in air the discrete liquid particles untiltheir solidification in the form of granules of magnesium or its alloy,coated with a shell of said salt addition, and granules of the same saltaddition.

2. A method of producing granules of magnesium or its alloys, includingheating liquid magnesium or its alloy to a temperature within the limitsof 670-720C; preparing a salt addition which is a mixture of magnesiumchloride with at least one component selected from the group consistingof alkali and alkaline-earth metal chlorides, and with 0.5-l0.0 weightper cent of at least one component selected from the group consisting ofmagnesium, sodium and alkaline-earth metal fluorides, the components ofsaid mixture being taken in such combination and in such quantitativecomposition that the initial crystallization temperature of the saltaddition is below that of magnesium, and its density at 670-730C isequal to 0.95-1 .2 of the density of liquid magnesium or its alloy;heating said salt addition to a temperature within the range 670-730C;simultaneously delivering said liquid magnesium or its alloy and thesalt addition in continuous streams into a centrifugal granulator;breaking the mixture of liquid magnesium or its alloy and the saltaddition into discrete liquid particles by the action of the centrifugalforce; cooling in air the discrete liquid particles until theirsolidification in the form of granules of magnesium or its alloy, coatedwith a film of said salt addition, and granules of the same saltaddition.

3. A method as set forth in claim 2, wherein liquid magnesium receivesthe salt addition comprising in weight per cent: 40-65 of KCl, -50 ofNaCl, 3-10 of MgCl up to 5.0 of CaCl up to 0.8 of F and not over 0.5 ofMgO.

4. A method as set forth in claim 2, wherein liquid magnesium alloyreceives the salt addition comprising in weight per cent: 30-50 of KCl,10-40 of MgCl up to 5.0 of CaCl up to 0.8 of F, but not over 0.8 MgO,3-15 of BaCl and the balance NaCl.

5. A method as set forth in claim 2, wherein liquid metal receives thesalt addition comprising sodium and potassium chlorides taken inproportion of 1.1 to 1.5 and sodium fluoride taken in the amount of05-10 weight per cent, the total content of magnesium, calcium andbarium chlorides not exceeding 5 weight per cent.

6. A method as set forth in claim 1, wherein liquid metal receives thesalt addition in the amount of 2.5-20 weight per cent to producegranulated magnesium including 50 per cent and more of spherical andellipsoidal granules.

7. A method as set forth in claim 2, wherein liquid metal receives thesalt addition in the amount of 2.5-20 weight per cent to producegranulated magnesium including 50 per cent and more of spherical andellipsoidal granules.

8. A method as set forth in claim 1, wherein liquid metal receives thesalt addition in the amount of 0.5-2.5 weight per cent to producegranulated magnesium including more than 50 per cent of elongatedgranules whose length is two times and more larger than their thickness.

9. A method as set forth in claim 2, wherein liquid metal receives thesalt addition in the amount of 0.52.5 weight per cent to producegranulated magnesium including more than 50 per cent of elongatedgranules whose length is two times and more large than their thickness.

10. A method as set forth in claim 1, wherein granules after beingcooled to l00-600C are subjected to a hydrochemical treatment during0.5-5 min in a [-10 per cent solution of potassium bichromate attemperature of 1035C with the weight proportion of the mixture andsolution from 1:1 to 1:20.

11. A method as set forth in claim 2, wherein granules after beingcooled are subjected to a hydrochemical treatment during 0.5-5 min in al-l0 per cent solution of potassium bichromate at temperature of 10-35Cwith the weight proportion of the mixture and solution from 1:1 to 1:20.

1. A METHOD OF PRODUCING GRANULES OF MAGNESIUM OR ITS ALLOYS INCLUDING:HEATING LIQUID MAGNESIUM OR ITS ALLOY TO A TEMPERATURE WITHIN THE RANGEOF 670*-720*C; PREPARING A SALT ADDITION WHICH IS A MIXTURE OF MAGNESIUMCHLORIDE AND AT LEAST ONE COMPONENT SELECTED FROM THE GROUP CONSISTINGOF ALKALI AND ALKALINE-EARTH METAL CHLORIDES TAKEN IN SUCH COMBINATIONAND IN SUCH QUANTITATIVE COMPOSITION THAT THE INITIAL CRYSTALLIZATIONTEMPERATURE OF THE SALT ADDITION IS BELOW THAT OF MAGNESIUM, AND ITSDENSITY AT 670*-730*C IS EQUAL TO 0.95-1.20 OF THE DENSITY OF LIQUIDMAGNESIUM OR ITS ALLOY; HEATING SAID SALT ADDITION TO A TEMPERATUREWITHIN THE RANGE OF 670*-730*C; SIMULTANEOUSLY DELIVERING SAID LIQUIDMAGNESIUM OR ITS ALLOY AND THE SALT ADDITION IN CONTINUOUS STREAMS INTOA CENTRIFUGAL GRANULATOR; BREAKING THE MIXTURE OF LIQUID MAGNESIUM ORITS ALLOY AND THE SALT ADDITION INTO DISCRETE LIQUID PARTICLES BY THEACTION OF THE CENTRIFUGAL FORCE; COOLING IN AIR THE DISCRETE LIQUIDPARTICLES UNTIL THEIR SOLIDIFICATION IN THE FORM OF GRANULES OFMAGNESIUM OR ITS ALLOY, COATED WITH A SHELL OF SAID SALT ADDITION, ANDGRANULES OF THE SAME SALT ADDITION.
 2. A method of producing granules ofmagnesium or its alloys, including heating liquid magnesium or its alloyto a temperature within the limits of 670*-720*C; preparing a saltaddition which is a mixture of magnesium chloride with at least onecomponent selected from the group consisting of alkali andalkaline-earth metal chlorides, and with 0.5-10.0 weight per cent of atleast one component selected from the group consisting of magnesium,sodium and alkaline-earth metal fluorides, the components of saidmixture being taken in such combination and in such quantitativecomposition that the initial crystallization temperature of the saltaddition is below that of magnesium, and its density at 670*-730*C isequal to 0.95-1.2 of the density of liquid magnesium or its alloy;heating said salt addition to a temperature within the range 670*-730*C;simultaneously delivering said liquid magnesium or its alloy and thesalt addition in continuous streams into a centrifugal granulator;breaking the mixture of liquid magnesium or its alloy and the saltaddition into discrete liquid particles by the action of the centrifugalforce; cooling in air the discrete liquid particles unTil theirsolidification in the form of granules of magnesium or its alloy, coatedwith a film of said salt addition, and granules of the same saltaddition.
 3. A method as set forth in claim 2, wherein liquid magnesiumreceives the salt addition comprising in weight per cent: 40-65 of KCl,25-50 of NaCl, 3-10 of MgCl2, up to 5.0 of CaCl2, up to 0.8 of F1 andnot over 0.5 of MgO.
 4. A method as set forth in claim 2, wherein liquidmagnesium alloy receives the salt addition comprising in weight percent: 30-50 of KCl, 10-40 of MgCl2, up to 5.0 of CaCl2, up to 0.8 of F1,but not over 0.8 MgO, 3-15 of BaCl2 and the balance - NaCl.
 5. A methodas set forth in claim 2, wherein liquid metal receives the salt additioncomprising sodium and potassium chlorides taken in proportion of 1.1 to1.5 and sodium fluoride taken in the amount of 0.5-10 weight per cent,the total content of magnesium, calcium and barium chlorides notexceeding 5 weight per cent.
 6. A method as set forth in claim 1,wherein liquid metal receives the salt addition in the amount of 2.5-20weight per cent to produce granulated magnesium including 50 per centand more of spherical and ellipsoidal granules.
 7. A method as set forthin claim 2, wherein liquid metal receives the salt addition in theamount of 2.5-20 weight per cent to produce granulated magnesiumincluding 50 per cent and more of spherical and ellipsoidal granules. 8.A method as set forth in claim 1, wherein liquid metal receives the saltaddition in the amount of 0.5-2.5 weight per cent to produce granulatedmagnesium including more than 50 per cent of elongated granules whoselength is two times and more larger than their thickness.
 9. A method asset forth in claim 2, wherein liquid metal receives the salt addition inthe amount of 0.5-2.5 weight per cent to produce granulated magnesiumincluding more than 50 per cent of elongated granules whose length istwo times and more large than their thickness.
 10. A method as set forthin claim 1, wherein granules after being cooled to 100*-600*C aresubjected to a hydrochemical treatment during 0.5-5 min in a 1-10 percent solution of potassium bichromate at temperature of 10*-35*C withthe weight proportion of the mixture and solution from 1:1 to 1:20. 11.A method as set forth in claim 2, wherein granules after being cooledare subjected to a hydrochemical treatment during 0.5-5 min in a 1-10per cent solution of potassium bichromate at temperature of 10*-35*Cwith the weight proportion of the mixture and solution from 1:1 to 1:20.